ANISOTROPIC FERROMAGNETIC QUANTUM DOMAINS

We study a model for anisotropic ferromagnetic quantum domain walls. T he large degeneracy of the ground state in the extreme anisotropic (Is ing) limit, associated with the translational invariance of the ''kink center,'' is lifted in the quantum system in a peculiar way. The crit ical point, at which the Hamiltonian is invariant under the quantum gr oup U-q [SU(2)], is exactly determined by a cluster method. We also fi nd the ground state wave function at the critical point. Some generali zations of these results for arbitrary spin and dimension are obtained .